Hanrahan confirmed on Saturday that he will undergo season-ending surgery to repair his torn flexor muscle tendon. Surgery on the flexor tendon typically carries a six- to nine-month recovery period, according to the reliever, although there’s no official timetable for his return.

The Red Sox acquired Hanrahan from the Pirates in the offseason to take over as closer after Andrew Bailey failed to do so after an injury-plagued season. Hanrahan endured a rough start to the season, sporting an 0-1 record with a 9.82 ERA in nine appearances.